Postretirement Benefit Plans - Fair Value of Plan Assets Held by Our Postretirement Benefits Plans (Detail) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		$ 286.9	$ 283.4	$ 278.0
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		279.0	273.9
Pension [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		85.8	97.6
Pension [Member] | International [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		46.3	53.0
Pension [Member] | Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		18.9	24.9
Pension [Member] | Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		121.1	97.1
Pension [Member] | Cash and other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		6.9	1.3
Pension [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		275.0	273.9
Pension [Member] | Level 2 [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		85.8	97.6
Pension [Member] | Level 2 [Member] | International [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		46.3	53.0
Pension [Member] | Level 2 [Member] | Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		18.9	24.9
Pension [Member] | Level 2 [Member] | Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		121.1	97.1
Pension [Member] | Level 2 [Member] | Cash and other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		2.9	1.3
Pension [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		4.0
Pension [Member] | Level 3 [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		0.0
Pension [Member] | Level 3 [Member] | International [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		0.0
Pension [Member] | Level 3 [Member] | Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		0.0
Pension [Member] | Level 3 [Member] | Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		0.0
Pension [Member] | Level 3 [Member] | Cash and other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset	[1]	4.0
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		7.9	9.5	$ 9.2
Other Postretirement Benefit Plan [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		2.6	2.8
Other Postretirement Benefit Plan [Member] | International [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		1.9	1.9
Other Postretirement Benefit Plan [Member] | Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		0.8	0.9
Other Postretirement Benefit Plan [Member] | Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		2.6	2.8
Other Postretirement Benefit Plan [Member] | Cash and other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		0.0	1.1
Other Postretirement Benefit Plan [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		7.9	9.5
Other Postretirement Benefit Plan [Member] | Level 1 [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		2.6	2.8
Other Postretirement Benefit Plan [Member] | Level 1 [Member] | International [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		1.9	1.9
Other Postretirement Benefit Plan [Member] | Level 1 [Member] | Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		0.8	0.9
Other Postretirement Benefit Plan [Member] | Level 1 [Member] | Fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		2.6	2.8
Other Postretirement Benefit Plan [Member] | Level 1 [Member] | Cash and other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan asset		$ 0.0	$ 1.1

[1] (a)Pension plan assets as of December 31, 2015 include an investment in a hedge fund acquired from Wolverine. The hedge fund is valued using broker quotes and classified within Level 3 of the fair value hierarchy due to the significance of unobservable inputs involved in the broker quote.